1. Field of the Invention
The present invention relates to an optical heterodyne scanning holography device capable of constructing an optical hologram in real time.
2. Description of the Prior Art
There is known conventionally, means to store phase and amplitude information concerning a reflected wave from an object to be holographed, one means being disclosed for example in Journal of the Optical Society of America A, Vol. 2, page 521, April 1985. In this prior method, laser lights each composed of a plane wave and a spherical wave both slightly different in temporal frequencies are superimposed to construct a Fresnel zone plate with which an object surface to be holographed is then scanned. A light scattered from the object surface, which includes a piece of information concerning the intensity and phase of the light scattered from the object surface is captured by a photodetector, photoelectrically converted, and reconstructed as an image of the object to be photographed on a target of a storage tube in synchronism with the scanning. The image of the object to be photographed is a hologram which is in turn irradiated with a flat laser light to reconstruct a hologram image.
The prior hologram reconstruction technique however has a difficulty in that real time reconstruction is impossible because the hologram must once be converted to a photographic film.
Therefore, reconstruction of a television transmission hologram is substantially impossible.